Generally, as disclosed in Patent Literature 1, a flow control device used to regulate the flow of fluid such as chemical solution and purified water used in manufacturing a semiconductor or the like includes: a housing which is formed of a resin material such as a fluororesin having superior chemical resistance so that the fluid would flow in a flow passage provided in the flow control device; a diaphragm which splits the housing in half; and a valve body which is linked with the movement of the diaphragm. In such a flow control device, one of the housing halves split by the diaphragm corresponds to a fluid chamber in which flow-controlled fluid flows while another housing half corresponds to a gas chamber to which control air is supplied, whereby the diaphragm is activated by the differential pressure generated between the fluid chamber and the gas chamber. The flow control device which activates the diaphragm by the differential pressure regulates the flow of the fluid flowing in the fluid chamber by making the valve body work with the movement of the diaphragm.